If he liked the Z8 and is looking for a similar experience, you gotta go with a roadster. How about an MZ4R?
On the M6, if you aren't particular about buying one new, those are one of the hardest hit with early depreciation in the current lineup. Get a used one instead and save 50% of MSRP

He should be able to find an M6 for less than a new Z4 Sdrive35i, and like the new Z4 the M6 does a nice job as luxury cruise machine and heavy hitter (500hp V10, remember). However, it's only a matter of time before we start seeing 400hp new Z4s, thanks to the turbos and piggybacks.

all very relative...to some enthusiasts, anything with leather, heated seats, climate control, interior body panels, carpet, instrumentation, air conditioning, and stereo systems is a pig.... so unless you're talking M3 CSL, any BMW is a pig

all very relative...to some enthusiasts, anything with leather, heated seats, climate control, interior body panels, carpet, instrumentation, air conditioning, and stereo systems is a pig.... so unless you're talking M3 CSL, any BMW is a pig

I dont think any BMW on the market today is sub 3000lbs is it?

Only their motorcycles are under 3000lbs

Granted with all the safety and techno stuff that all car manuf. are adding, there are very few cars for sale (in the US), that are under 3,000 and have an engine larger than a lawnmower.